code: def __len__(self) -> int:
      return len(self.higher_vars)
  
file_path: dedupe/dedupe/variables/categorical_type.py
imports: from __future__ import annotations
  from categorical import CategoricalComparator
  from dedupe import predicates
  from dedupe._typing import PredicateFunction, VariableDefinition
  from dedupe.variables.base import DerivedType, FieldType
label_desc: Use image node_id 3 for calling the CategoricalType obj's underlying member method code with example usage: obj.__len__() and returns: len